Conveyor leveling system

ABSTRACT

Systems for automatically leveling a base frame of a bulk material transport conveyor include radial travel wheels mounted on generally opposing sides of the base frame that can move from a raised position above the ground to a lowered position in contact with the ground to permit radial travel of the conveyor. Actuators normally used to raise or lower the radial travel wheels may be actuated automatically by a controller in response to a signal from an inclination and/or limit sensor mounted on the conveyor that represents a non-level orientation of the conveyor, to level the base frame.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/751,723, filed Jan. 24, 2020, which is a divisional of U.S. patentapplication Ser. No. 16/414,151, filed May 16, 2019, U.S. Pat. No.10,583,993, issued Mar. 10, 2020, which is a continuation of U.S. patentapplication Ser. No. 15/233,629, filed Aug. 10, 2016, U.S. Pat. No.10,315,853, issued Jun. 11, 2019, which claims the benefit of U.S.Provisional Patent Application Ser. No. 62/311,515, filed Mar. 22, 2016and U.S. Provisional Patent Application Ser. No. 62/203,222, filed Aug.10, 2015 and, which are incorporated by reference herein.

TECHNICAL FIELD

This disclosure pertains generally to systems and methods forautomatically leveling the moving base frame of a bulk material conveyortransport system.

BACKGROUND

Conveyor systems, particularly radial travel stacking conveyors includewheels mounted on an axle that allow the conveyor to pivot about a pivotpoint. In operation, such conveyors may become unstable or imbalanced asthe wheels encounter un-level ground conditions.

Thus there is a need in the art for conveyor leveling systems andmethods for improving, inter alia, stability or balance of a conveyor.

DESCRIPTION OF THE FIGURES

FIGS. 1A and 1B illustrate two positions of a portion of one embodimentof a base frame of a conveyor undercarriage.

FIG. 2 is a flow chart corresponding to one embodiment of a conveyorleveling method.

FIG. 3 is a partial hydraulic piping schematic of one embodiment of aconveyor leveling system.

FIG. 4 is a system schematic of the conveyor leveling system of FIG. 3.

FIGS. 5A and 5B are a pair of annotated images comparing performance ofone embodiment of the conveyor leveling system as applied to a baseframe assembly passing over the crest of a mound of earth.

FIGS. 6A and 6B are a pair of annotated images comparing performance ofone embodiment of the conveyor leveling system as applied to a baseframe assembly passing over the crest of a mound of earth.

FIG. 7 is a plan view of an embodiment of a conveyor having radialtravel wheels.

DETAILED DESCRIPTION

In the following description, references to particular equipment ortypes of equipment should be understood as illustrative but notlimiting. For example, references to a programmable logic controller orPLC should be understood as including any form of computerized orelectronic equipment capable of performing as described.

Bulk material conveyor transport systems are used in stockpiling rock,grain, and/or other aggregate material. In general, such conveyorsystems include a support frame or undercarriage, a conveyor assemblymounted on the support frame at a feed end of the base frame, and asupport strut that extends between the base frame and the conveyorassembly. The base frame may include a first set of wheels for movingthe conveyor to a work site, and a second set of wheels that permit theconveyor to move radially relative to the feed end of the base frame.One version of a conveyor system with radial travel capabilities isgenerally described in U.S. Pat. No. 5,515,961 (the entire contents ofwhich is incorporated by reference as if fully set forth here) andavailable commercially from Superior Industries, Inc. of Morris, Minn.under the tradename TeleStacker®. The TeleStacker® system is an exampleof what is known as a radial stacking conveyor. Such a system generallycomprises a heavy-duty base frame which supports the conveyor assembly,which frame has a first set of axles and wheels for transportation inconventional forward or reverse directions, such as over a highway(i.e., in an X direction such as into or out of the page in FIG. 1A). Aportion of the base frame may also include a second set of wheels oneither end of a base frame known as radial travel wheels that permitside-to-side movement of the conveyor system (i.e., in a Y directionsuch as to the left or right in FIG. 1A). It should be appreciated thatin some embodiments, the conveyor pivots radially on the radial travelwheels about a rearward pivot point such that the Y direction isgenerally tangential to the radial movement of the conveyor. FIG. 7illustrates a plan view of an embodiment of a conveyor 700 supported onbase frame 40. The illustrated conveyor 700 travels along a radial pathR (about rear pivot P) of the conveyor 700 supported on base frame 40(e.g., as it creates stockpile Sr). An exemplary direction X isillustrated tangential to the radial path R and transverse to anexemplary direction Y (e.g., along a transport direction of the conveyor700 in a transport mode). In alternative embodiments, the levelmeasurements and leveling operations described herein are performed onconveyors which travel side-to-side (e.g., to create a transversestockpile) rather than radially.

In one embodiment, each set of radial travel wheels are carried on anaxle mounted on an outrigger-like frame connected on opposite sides ofthe base frame. In one embodiment, the outrigger-like frames arepivotally connected to the base frame. In this embodiment, the radialtravel wheels are brought into engagement with the ground by anactuator, such as a hydraulic cylinder, that pivots the outrigger framefrom a raised position to a lowered position to transfer the weight ofthe conveyor system from the first set of wheels to the radial travelwheels (which may be referred to as “FD” axles and wheels,respectively). The outrigger frames may also be referred to as the “leftFD” and “right FD” assemblies. The FD wheels are generally directed inthe left and right directions, roughly perpendicular to the direction ofthe transport wheels. (A minor amount of variation from perpendicularmay accommodate the radial motion described further below.) Other meansfor a set of wheels to move stacking conveyors in a radial direction arealso known. The method of leveling disclosed herein is not intended tobe limited to one radial stacking conveyor system.

For ease of reference, one embodiment of the leveling system will bedescribed by reference to the TeleStacker® system. Once the conveyorsystem arrives at the jobsite, each of the FD outrigger frames may behydraulically lowered (“folded down”) to a position which places theseparate FD wheels below the transport wheels, thus raising the baseframe enough to lift the transport wheels above ground. The base framemay then move radially from side to side on the generally left- andright-directed FD wheels, to vary the location of the discharge end ofthe conveyor. That is, the wheeled end of the conveyor moves radiallyback and forth on the FD wheels so that the conveyor belt, supported ata distance above the base frame by a truss, discharges bulk material toform long rows of stacked material. See, for example, U.S. Pat. No.7,470,101, the entire contents of which are incorporated by reference.

Some systems and methods described herein provide for control (e.g.,automation) of the actuation of actuators (e.g., the hydraulic cylindersthat control the deployment of each FD assembly) to maintain the baseframe level while the base frame traverses uneven terrain or changinggrades in its back-and-forth travel. In one embodiment, a level sensor420 (e.g., inclinations sensor) is mounted on the conveyor, such as onthe base frame, and communicates a value indicative of the orientationof base frame 40 relative to level in the Y direction to a computer suchas a programmable logic controller (PLC) or the equivalent. Sensor 420can be mounted on other structures of the conveyor so as to monitor thelevel status of the base frame. Programming determines which actuator toraise or lower to bring the base frame back toward a level position.Optionally, an additional sensor or sensors may provide inputs to thePLC (or equivalent) to determine other variables such as maximum orminimum cylinder extension limits and ground clearance. The conceptsdescribed herein may be embodied as a system, or performed as a method,without loss of generality.

Structure

Referring to FIGS. 1A and 1B, which illustrate one embodiment only, awheeled base frame 40 comprises three main components: a central baseframe portion 42, and two frames 52 a, 52 b (e.g., outrigger-typeframes) pivotally mounted on opposing sides of the central base frameportion 42. Each outrigger frame 52 a, 52 b is preferably wheel-bearing,e.g., supports one or more axles 76 and wheels 60, and in the exemplaryembodiment shown, each is pivotably connected to the central base frameportion 42 by a pivotal axis 72 so as to move (e.g., pivot) relative tothe central base frame 42. Thus, each outrigger frame 52 a, 52 b pivotsfrom a transport position, shown in FIG. 1B, in which the central baseframe portion 42 is supported on transport wheels 44 and wheels 60 arelifted above the ground, to a radial travel position, shown in FIG. 1A,in which the wheels 60 are lowered to the ground to support the centralbase frame portion 42 with the transport wheels 44 off of the ground.Conversely, in the radial travel position of FIG. 1A, each outriggerframe is lowered until the wheels 60 are below the level of the centralbase frame portion 42 by an amount sufficient to lift the base frame,and thus wheels 44, off of the ground, such that the base frame 40 ismovable in a radial direction described above. For example, in theradial travel position, in one embodiment the lower surface of thecentral base frame portion 42 is raised from about 11 inches ofclearance above ground to about 22 inches of clearance above ground.

In one embodiment, the base frame includes a support 46 that extendsupwardly from the central base frame portion 42. The support 46 may befabricated from tubular, solid or other structural shapes and configuredin a variety of manners although it is preferably equipped with a pairof vertical members 47 each extending upwardly from the central baseframe 42, a horizontal cross-member 48 which may support the conveyorassembly (not shown) such as during transport and storage, and angledsupport reinforcement members 49. Any of these members could be formedfrom diagonal cross-bracing, curved material, solid gusset plates, oropen portions of a structural plate. In various embodiments, the slottedvertical members 47 and/or the reinforcements may be omitted. Thecentral base frame portion 42 is preferably pivotably linked to each ofthe outrigger frames 52 a, 52 b by a first pivot such as asupport-mounted pin 54, an actuator 56, such as a hydraulic cylinder,and a second pivot such as an outrigger cylinder pin 62 attached to theouter end of the respective outrigger frame. In other conveyor systemsthat employ a different outrigger-like radial travel arrangement,support 46 may not be utilized. By way of example, in one embodiment alevel sensor 420 is mounted on the central base frame portion 42 tomonitor the level status of the base frame 40 in the Y direction.

Sequence

A system monitors and adjusts the position of the base frame 40 whilethe base frame is in the radial travel position to keep base frame 40level or as close to level as possible in the Y direction. In additionto providing improved stability of the conveyor assembly or truss abovethe base frame, keeping the base frame level or close to level mayimprove conveyor belt tracking and alignment issues. It should beappreciated that a level base frame does not guarantee belt alignment.There are several factors that can cause belt misalignment, includingidler positioning, head or tail pulley position (angle), materialplacement on the belt, and belt splice accuracy or belt camber.

In one embodiment, the monitoring and adjustment system controls theactuators 56 to keep the base frame at or near a level orientation inthe Y direction. The system is able to adjust the orientation of baseframe 40 to level at least to a slope of 5.25% grade (3°). Among othereffects, providing a level operating orientation preferably tends toalleviate the effect of non-level truss on belt tracking.

In some embodiments, the transport wheels 44 may contact the ground whenthe actuators 44 are extended to a first extent less than a maximumextent (e.g., stroke length). For example, FD cylinders may have a 36″stroke length, but the transport wheels may contact the ground atapproximately 30″ of stroke extension. Thus, in such embodiments, inorder to keep the transport wheels off the ground while the base frameis in the radial travel position (e.g., to keep the transport wheelsfrom dragging), a maximum orientation change (e.g., 5.25% or 3 degrees(+/−) clearance) may be available to maintain a level orientation ofbase frame 40. Depending on the direction of the slope, actuator 56disposed on the lower side of the base frame 40 is preferably retainedin a fully extended position. Full extension of the actuator 56 on thelower side of base frame 40 preferably ensures sufficient (e.g, maximum)clearance for the transport wheels 44 over the grade of the ground beingtraversed. The actuator 56 disposed on the higher side of the base frame40 is preferably at least partially retracted (e.g., to lower the baseframe relative to the radial wheel 60) to bring the base frame back intoa level orientation. In some embodiments, the actuators 56 are onlyretracted to a partial retraction limit (e.g., retraction ofapproximately 5″ or less) during leveling operations to ensure clearanceof the base frame relative to the ground. It should be appreciated thatfor embodiments of a conveyor system that include transport wheels 44,retraction of the actuators by more than the partial retraction limitmay allow one or more transport wheels 44 to drag on the ground (e.g.,when negotiating a surface having a slope at or above the maximumorientation change such as 5.25% grade).

Thus, in one embodiment, in order to maintain the base frame above theground sufficient to prevent the transport wheels from dragging and tooptimize (e.g., maximize) the maximum orientation change, a firstactuator 56 (e.g., on the low side of the base frame) is fully extendedwhile a second actuator (e.g., on the high side of the base frame) isretracted. If during leveling operations the orientation angle of thebase frame crosses the horizontal plane (e.g., changes to an anglehaving an opposite sign as measured from a horizontal plane), the secondactuator (now on the low side of the base frame) preferably extendsfully before the first actuator (now on the high side of the base frame)retracts if more correction is required. This result may be accomplishedin any manner consistent with the principles disclosed herein.

FIG. 2 illustrates one embodiment of sequence 100 by which thecontroller (PLC) adjusts the base frame 40 toward a level orientation asit traverses uneven terrain (e.g., either above or below the surroundinglevel terrain). Initially, at 110, the controller uses a level sensorinput to determine whether the base frame is level. If so, thecontroller checks at 120 for whether the base frame is travellingradially, as the controller performs additional tasks if that is thecase. Alternatively, the controller begins sensing level when it detectsradial travel of the base frame. The controller may determine whetherthe base frame is travelling radially by determining whether thecontroller is commanding a radial movement (e.g., whether a command hasbeen entered to command radial movement), or in other embodiments byusing a wheel speed encoder or a kinematic sensor such as a gyroscope,radar, or GPS receiver. If the base frame is not travelling radially,the controller preferably exits (e.g., terminates and/or restarts thesequence 100) at 130 without adjusting the orientation of the baseframe. But if the base frame is travelling radially and is not level(110), the controller at 140 preferably uses the sensor input signal todetermine if the angle measurement is greater or less than 180°. In thiscontext, the 0° direction is taken to be a first side of the base frame,e.g., relating to the right FD such that deviation from 180° representsthe amount of upward or downward slope being encountered by theopposite, second side of the base frame, e.g., relating to the left FD.

If the angle measurement is greater than 180°, the “left FD” frame ofthe base frame is encountering a decline or downward slope relative tolevel. Thus the sequence preferably commands a lowering of the “left FD”frame of the base frame (e.g., to follow downward terrain). Thecontroller preferably determines at 150 whether the “left FD” frame isalready fully extended. If the “left FD” frame is not fully extended,then there may be additional extension available to enable the “left FD”frame to be further extended to lower its associated wheel toaccommodate the terrain and maintain the entire base frame at levelposition. Thus if the “left FD” frame is not fully extended, thecontroller at 151 preferably further extends the “left FD” portion, andif there is sufficient extension available to achieve the 180° levelcondition again (as indicated by the level sensor), then at 152 thecontroller preferably stops extending the “left FD” actuator at thatlevel condition, and resumes monitoring for a deviation from that levelcondition (120, 110). If the “left FD frame has reached full extensionand the 180° level has not been reached (153), the controller at 154preferably retracts the “right FD” actuator, which effectively lowersthe related right side of the base frame to accommodate the lowering ofthe left side caused by the downward slope. The controller monitors at155 (using the level sensor input) whether the level condition isreached before the “right FD” frame of the base frame reaches itsretract limit. If the base frame is not at the 180° level condition whenthe “right FD” frame reaches its retract limit (156), the controllerensures at 157 that no further retraction of the “right FD” portion ispossible until after the entire base frame is at the 180° levelcondition again, to ensure that the central portion of the base framehas sufficient clearance over the terrain for continued radial travel.

The operations are very similar if the level sensor indicates to thecontroller that the angle measurement is less than 180°, except that inthis case such a measurement indicates that the “left FD” frame of thebase frame is encountering an incline or upward slope relative to level.In this case, the controller preferably lowers the “left FD” frame ofthe base frame to follow the upward terrain, but preferably only afterit ensures that the “right FD” actuator is fully extended will it allowthe “left FD” portion to be retracted to maintain the base frame atlevel position. Thus, the controller at 160 will determine if it ispossible to further extend the “right FD” actuator, and if there issufficient extension available (161) to achieve the 180° level conditionagain (as indicated by the level sensor), the controller (162) will stopextending the “right FD” portion at that level condition, and resumemonitoring for a deviation from that level condition (120, 110). If the“right FD” frame has reached full extension (163), the controller at 164will retract the “left FD” portion, which effectively lowers the leftside of the base frame to accommodate the raising of the right side ofthe base frame (e.g., caused by upward ground slope). The controllermonitors at 165 (e.g., using the level sensor input) whether the 180°level condition is reached before the “left FD” portion of the baseframe reaches its fully retracted limit. If the base frame is not at the180° level condition when the “left FD” frame reaches its retract limit(166), the controller ensures at 167 that no further retraction of the“left FD” portion is possible until after the entire base frame is atthe 180° level condition again, to ensure that the central portion ofthe base frame has sufficient clearance over the terrain for continuedradial travel.

As described herein, the limit of retraction or extension of anoutrigger frame 52 a, 52 b of the base frame 40 may depend on theretraction or extension limit of the actuator 56 used to raise and/orlower the frame, and may additionally or alternatively depend on theretraction or extension limit of the frame itself. In either case, theretraction or extension limit may be a physical limit at which the frameand/or actuator cannot be physically retracted or extended further, ormay comprise another limit (e.g., an empirically determined limit orsafety limit) which may be of lower magnitude than a physical limit.

Level Sensor

In one embodiment, an inclination or level sensor may be mounted on thebase frame 40 to send the level position to a controller such as a PLC.Based on the level position information coming from the inclinationsensor, the PLC program preferably makes a decision on which FD cylinderto raise or lower to bring the base frame back into a level position.Additionally, there may be a proximity sensor located on one or bothpivoting outrigger frames 52 a, 52 b which sends a signal to the PLC totell the PLC program the actuators 56 maximum and/or minimum travellimits on the stroke of each actuator. Furthermore, there may be yetanother sensor (e.g., proximity sensor) mounted on the base frame 40 todetect the ground clearance for the travel wheels, to make sure theconveyor will not get stuck based on the changing conditions of theterrain the radial wheels will drive on, e.g., ruts formed by the otherwheels, weathering of the terrain, and so on. In alternativeembodiments, the angle of level correction may be greater or less thanabout 3 degrees or 5.25% grade. The level sensor may be mounted to thecentral base frame portion 42 of the base frame and/or to the support46. The level sensor is mounted to a portion of the conveyor (e.g., thebase frame) that moves rigidly with the conveyor truss (e.g., when theconveyor truss is not being raised or lowered, extended or retracted,such as during material transfer operations of the conveyor). Inalternative embodiments, the level sensor may be mounted to otherlocations on the base frame or elsewhere on conveyor, e.g., to a trussof the conveyor. In embodiments in which the level sensor is disposedremotely from the base frame, the level sensor may be in wirelesscommunication with the controller.

In embodiments including a proximity sensor (e.g., mounted to the baseframe such as on the central base frame 42, and disposed to measure adistance between the base frame and/or the transport wheels and theground surface), the proximity sensor may be used additionally oralternatively to determine an adjustment to make to the actuators 56.

Hydraulics

To implement a base frame leveling system, in one embodiment a hydraulicsystem may incorporate automatic leveling without affecting the otherhydraulic functions on the bulk material conveyor transport system. Inone embodiment, the hydraulic system controls the hydraulic fluid (e.g.,oil) flow to each hydraulic cylinder based on commands from the PLCprogram. Existing systems for raising and lowering may be sized tooperate one function at a time (with the possible exception of raisingboth cylinders during a raise cycle). If so, to operate theauto-leveling system described here, in one embodiment the single flowsource is split to allow the cylinders to operate while the radialtravel wheels are also in operation. In one embodiment, the reactiontime of the cylinders is reduced to provide stability to the truss inthe raised position, but also to prevent over-reaction during levellingadjustments.

In one embodiment two hydraulic pumps on the main hydraulic power unit(e.g., a tandem gear pump) are utilized to achieve the desired speed forthese two control functions. In this embodiment, the cylinder controlvalves are also isolated from the rest of the control valves such thatthe cylinder control valves have an isolated and reduced flow rateduring leveling operations. This may be achieved in any known manner,but most preferably is achieved by having two independent pumpsconnected with two independent valve manifolds. In some embodiments inwhich a pump is sized for the flow rate to be provided for theactuators, there may be no need for flow controls to alter the flowrate. Elimination of flow controls could eliminate unnecessary heat inthe system due to alteration of flow.

In yet another embodiment, in order for the cylinders to operate atnormal speed when making a raise cycle, there is an additional 2position (bypass) valve controlled by the PLC that will open both pumpflows to either valve manifold as needed. In one non-limiting example,such a bypass valve allows the cylinders to operate between a use of 1.2GPM during leveling operations and as much as 9 GPM for faster cycletime during the raise cycle as well as regular manual control operation.Each valve manifold has the ability to use the maximum flow rate ifdesired, as that may be controlled by the 2 position bypass valve andone of the two dump valves on each valve bank manifold. This mode ofoperation also can be managed through the PLC program.

As shown in the hydraulics schematic of FIG. 3, each of twodouble-acting actuators 4 (e.g., hydraulic FD cylinders) is attached byconventional fittings 21 and hoses 16, 17 to a conventional source 310of hydraulic pressure and control. Each actuator 4 is controlled by avalve 18 such an over-center valve. One example of a PLC is the AllenBradley MicroLogix 1400 available from Rockwell Automation. One exampleof a level sensor (e.g., inclination sensor) is the P&F modelINX360D-F99-I2E2-V15 available from Pepperl & Fuchs in Mannheim,Germany. In various embodiments, the level sensor may comprise a tiltsensor and/or gyroscope. If used, one example of a proximity sensor isthe P&F model NEB12-18GM50-E2-V1 available from Pepperl & Fuchs inMannheim, Germany. Additional details of the operation of thesecomponents is provided herein.

In embodiments employing two pumps as described above, a first pumppreferably has a displacement of 1.03 cubic inches of displacement(“CID”), which may produce approximately 7.75 gallons per minute (“GPM”)output. A second pump preferably uses a second pump portion having adisplacement of 0.16 CID which only produces approximately 1.2 GPMoutput.

Limit Sensor

To limit the travel of the actuators 46 during leveling operations, itis desirable to incorporate a proximity sensor (e.g., induction sensor)on each side of the outrigger frame 52 a, 52 b to sense a “lug” or otherfeature mounted to an adjustable bracket on the FD arm assembly. Thisallows for precise set-up for maximum operating angle adjustment, i.e.,to ensure that travel of the cylinders is limited. For example, in onealternative embodiment, as confirmed by testing the use of a magneticpiston in the FD cylinder and external magnetic field sensors (Pepperl &Fuchs model MB-F32-A2-V1), such equipment proved effective. If proximitysensors are omitted, a software-based limit on the travel of thecylinders may be used in the alternative, if desired.

Speed Control

It is preferred to control the speed (e.g., flow rate) of the actuators56 in the normal operating condition. This is because rapid changes inangle can cause overcorrection by the control logic. One method toovercome this problem is to reduce the flow rate to the FD cylinders inany convenient manner. While a single gear pump orpressure-compensator-controlled piston pump could be used, a tandem gearpump also can be used. Such an embodiment may benefit from use of a 15horsepower motor instead of a 10 horsepower motor. A major advantage ofthe tandem fixed gear pump design is that the pump provides a consistentflow rate in varying climates and environments. Alternative methods ofusing special pump controls and in-line flow controls may rely onconsistent adjustment settings during the installation. In someembodiments, a pressure compensating pump control and/or flow controlsmay be used to adjust speed, which controls may consume energy and emitheat. Flow controls may be used in some embodiments to control radialtravel and may also create additional heat. In some embodiments an oilcooler may be used prevent oil from reaching excessive temperatures.

In another embodiment, a single valve manifold is used, which may reducethe size required as compared to two individual manifolds. One exemplarymanifold is designed with two pressure inlets and a single common tankoutlet. The tandem pump preferably provides two independent flow ratesto each manifold inlet, which are internally separated by a two position(on-off) valve cartridge that will either combine the flows of bothpumps to all the valve stations, or split the circuit into individualcircuits and provide normal flow rates to the radial travel wheelcircuit (and other hydraulic circuits) while at the same time allowingfor a reduced flow rate to either levelling actuator (e.g., FDcylinder).

It should be noted that when in set-up mode, the two position (on/off)cartridge is preferably actuated and opens the path for the flows fromboth pumps to combine and provide the maximum flow rate to the FDcylinders.

Automation Controls

Automation controls allow an operator to turn the leveling (e.g.,automatic leveling) function on or off through the set up touch screen.This means that whether the operator is running an automated pileprogram or manual control, the leveling function can be turned on oroff. When the leveling function is active, the PLC preferably reads andevaluates the signal from the inclination sensor 420 (e.g., located onthe base frame). The PLC program logic preferably uses this feedback tocontrol valves in fluid communication with each chamber of each levelingactuator (e.g., the rod end and head end of each actuator) tocontinuously adjust the FD cylinder position and maintain a level baseframe.

System Embodiments

An exemplary system 400 for leveling a conveyor (e.g., according tovarious methods described herein) is illustrated schematically in FIG.4, in which solid lines indicate fluid communication between components(e.g., for transfer of pressurized hydraulic oil) and dotted linesindicate data communication (e.g., electrical, electronic, wireless)between components (e.g., for transfer of signals and other commands). Afirst pump 440 (e.g., a gear pump such as a tandem pump) supplies fluid(e.g., hydraulic oil) to actuators 56-1, 56-2 (e.g., FD cylinders). Insome embodiments, control valves 410-1, 410-2 (e.g., flow controlvalves) control a flow rate and/or pressure of fluid supplied to theactuators 56-1, 56-2, respectively. The control valves 410-1, 410-2and/or pump 440 are in data communication with and controlled by aprogrammable logic controller (PLC) 450. A level sensor 420 is in datacommunication with the PLC 450 for sending level signals to the PLC 450.

In some embodiments, a second pump 445 is in fluid communication with acontrol system 470 having control valves for controlling other hydraulicfeatures of the conveyor (e.g., cylinders for raising and lowering theconveyor and/or motors for controlling radial travel of the conveyor).The second pump 445 may be in data communication with the PLC 450 orwith another controller.

Example

FIGS. 5A and 5B and FIGS. 6A and 6B are a pair of annotated picturescomparing performance of one embodiment in two separate runs ofidentical performance conditions, except for the operation of theleveling system. FIGS. 5A, 5B, 6A, 6B demonstrate a base frame assemblypassing over a mound of unevenly piled earth 510 causing the base frameassembly to deviate from the level ground 520 surrounding the mound ofearth. The amount of deviation from level as illustrated by line 600depends on the position of the radial travel wheels 530, 540 on themound, and may not be the same on one side of the mound as compared tothe other, i.e., the mound may not be symmetric with respect to themidpoint or crest of the mound.

An automatic system as described above was assembled at full scale andtested to demonstrate its principles of operation and effectiveness.FIGS. 5A and 6A, reflect a run in which the automatic leveling system isturned on, and FIGS. 5B and 6B reflect a run in which the auto-levelingsystem was turned off. The images of FIG. 5A show base frame 500 passingfrom right to left over the mound 510, i.e., the “leading” wheels 530 onthe mound 510 and the “lagging” wheels 540 still on level ground 520.The images of FIG. 5B show the base frame 500 centered over the mound510 moving from left to right, i.e., both wheels 530, 540 on a portionof the mound 510 as opposed to level ground 520.

In FIGS. 5A, 5B, 6A, 6B a dashed reference line 600 is drawn betweenpoints on the base frame 500 to illustrate the difference in position ofthe base frame 500 as a whole (or, in other embodiments, only portionsof the base frame 500 which are controlled by the leveling system) dueto the leveling system being either on (upper image) or off (lowerimage). In FIGS. 5A, 5B, the base frame 500 is at the same locationrelative to the mound 510, and thus all conditions affecting the overalldegree of level of the base frame 500 are essentially the same exceptfor the use (upper image) or lack of use (lower image) of the levelingsystem. FIGS. 6A and 6B also show base frame 500 at the same locationrelative to mound 510. By comparing the lines 600 it may be observedthat the leveling system has a substantial impact on the degree to whichthe base frame 500 remains level despite passing over the uneven terraincaused by the mound of earth 510. For example, note the difference inangle of the lines 600 at the leading wheel assembly, i.e., the leftmostassembly in FIGS. 5A-5B (supporting wheels 530) and the rightmostassembly in FIGS. 6A-6B (supporting wheels 540).

Further Embodiments

In some embodiments, an additional actuator or actuators is/are used tolevel the conveyor. In such embodiments, actuators for raising orlowering radial travel wheels to a transport position may not be usedfor leveling the conveyor. Some embodiments may not include actuatorsfor raising or lowing radial travel wheels to a transport position.

In some exemplary embodiments in which an actuator or actuators otherthan the FD actuators are used to level the conveyor, a levelingactuator may be disposed to adjust the orientation, position and/orconfiguration of the base frame (e.g., of the support 46). For example,the support 46 may be slidingly or pivotally mounted to the central baseframe 42 and one or more leveling actuators may be employed to modify aheight and/or orientation of the support 46.

It should be appreciated that although certain methods described hereinpreferably determine whether the conveyor (e.g., base frame) is movingradially, such methods do not necessarily include determining thedirection of radial movement, nor do systems performing such methodsnecessarily include devices or structure for determining such direction.However, some embodiments may additionally or alternatively determine adirection of travel (e.g., radial travel) of the conveyor (e.g., baseframe) in order to determine an appropriate leveling action (e.g.,extension or retraction of an actuator such as an FD actuator).

Although the base frame embodiments illustrated herein are shownsupported by wheels, in other embodiments, the base frame may besupported by other apparatus such as tracks for radial travel (and/ortransport). In still other embodiments, the base frame may not travelradially during operations and/or may be a stationary conveyor withoutwheels and/or tracks.

Based on the description above, a method and system for leveling aconveyor has been described. One embodiment involves a method ofleveling a radial stacking conveyor. This type of conveyor has radialtravel wheels connected on generally opposing sides of a base frame thatare height adjustable by actuators. A first actuator is associated witha first set of radial travel wheels on a first side of the base frame,and a second actuator is associated with a second set of radial travelwheels connected on a second side of the base frame. The first andsecond actuators are able to adjust a vertical spacing between theradial travel wheels and the base frame, the method of levelingcomprises providing a level sensor on the conveyor; sensing a signalfrom the level sensor indicating that the base frame is not level;performing a first adjustment step comprising raising a low side of thebase frame; sensing the signal from the level sensor to determine if thefirst adjustment step leveled the base frame; and performing a secondadjustment step if the first adjustment step did not level the baseframe, the second adjustment step comprising lowering a high side of thebase frame towards level.

Another embodiment is a leveling system for a radial stacking conveyorhaving height adjustable radial travel wheels connected on generallyopposing sides of a base frame. The base frame comprises a firstactuator associated with a first set of radial travel wheels on a firstside of the base frame, and a second actuator associated with a secondset of radial travel wheels connected on a second side of the baseframe. Each of the first and second actuators is in fluid communicationwith a valve that controls an extension of the respective first andsecond actuators. The first and second actuators are able to extend andretract to adjust a vertical spacing between the radial travel wheelsand the base frame. The leveling system further comprises a level sensormounted to the conveyor that is able to generate a level sensor signalindicating that the orientation of the conveyor relative to level, and acontroller that is in data communication with the level sensor and thevalves of the first and second actuators. The controller is capable ofperforming a first leveling sequence to level the base frame comprisingdetecting when one side of the base frame is below level; extending oneof the first and second actuators on a low side of the base frame untilthe level sensor signal indicates the conveyor is level or until theactuator on the low side of the base frame is extended by a thresholddistance. The controller is further capable of performing a secondleveling sequence if the first leveling sequence does not level the baseframe comprising retracting one of the first and second actuators on ahigh side of the base frame to lower the high side towards level.

We claim:
 1. A leveling system for a radial stacking conveyor havingradial travel wheels connected on generally opposing sides of a baseframe, the base frame comprising a first actuator associated with afirst set of radial travel wheels on a first side of the base frame, anda second actuator associated with a second set of radial travel wheelsconnected on a second side of the base frame, the first and secondactuators able to extend and retract to adjust a vertical spacingbetween the radial travel wheels and the base frame, the leveling systemcomprising: at least a first level sensor mounted to the conveyor, thefirst level sensor configured to generate a level sensor signalindicating an orientation of the conveyor relative to level; a flowcontrol system in fluid communication with at least the first actuator,the flow control system configured to control an extension of at leastthe first actuator; and a controller in data communication with saidfirst level sensor and the flow control system, said controllerconfigured to modify an operating state of at least one component ofsaid flow control system, wherein modification of said operating statemodifies an actuator extension of said first actuator, whereinmodification of said actuator extension modifies said orientation of theconveyor relative to level.
 2. The leveling system of claim 1, furthercomprising: a proximity sensor, said proximity sensor being in datacommunication with said controller, wherein said proximity sensor isconfigured to generate a proximity signal, said proximity signal beingindicative of an extension of the first set of radial travel wheels. 3.The leveling system of claim 2, wherein said proximity signal isindicative of said actuator extension.
 4. The leveling system of claim3, wherein the proximity sensor is mounted adjacent to said firstactuator.
 5. The leveling system of claim 1, further comprising: a firsthydraulic pump, said first hydraulic pump in fluid communication withsaid first actuator; a conveyor lift cylinder disposed to modify aheight of a conveyor truss; and a second hydraulic pump, said secondhydraulic pump in fluid communication with said conveyor lift cylinder.6. The leveling system of claim 5, wherein said first and secondhydraulic pumps together comprise a tandem gear pump.
 7. The levelingsystem of claim 1, wherein the base frame has a transport configurationand a radial travel configuration, wherein in said radial travelconfiguration the base frame is supported by said first and second setsof radial travel wheels, wherein the first and second actuators are ableto alternately raise and lower the first and second sets of radialtravel wheels between the transport configuration and the radial travelconfiguration, the leveling system further comprising: a transportwheel, wherein in said transport configuration the base frame is atleast partially supported by said transport wheel.
 8. The levelingsystem of claim 1, wherein said first level sensor comprises aninclination sensor.
 9. The leveling system of claim 1, wherein said flowcontrol system comprises at least one valve.
 10. The leveling system ofclaim 8, wherein said at least one valve comprises an over-center valve.11. The leveling system of claim 1, wherein said first and secondactuators have a radial travel configuration in which the first set ofradial travel wheels are lowered such that one or more transport wheelsof the conveyor are lifted off the ground.
 12. A radial stackingconveyor, comprising: a base frame; first and second sets of radialtravel wheels connected on generally opposing sides of said base frame;at least a first actuator operably coupling said first set of radialtravel wheels to said base frame; at least one flow control device influid communication with the first actuator, the flow control deviceconfigured to control an extension of said first actuator; and acontroller in data communication with said flow control device, saidcontroller configured to modify an operating state of said flow controldevice, wherein modification of said operating state modifies anactuator extension of at least said first actuator, wherein modificationof said actuator extension modifies an orientation of the conveyorrelative to level, wherein said first actuator has a travelconfiguration in which the first set of radial travel wheels are raisedoff the ground such that the conveyor rests at least partially on one ormore transport wheels, wherein said first actuator has a radial travelconfiguration in which the first set of radial travel wheels are loweredsuch that the one or more transport wheels of the conveyor are liftedoff the ground.
 13. The radial stacking conveyor of claim 12, furthercomprising: a proximity sensor, said proximity sensor being in datacommunication with said controller.
 14. The radial stacking conveyor ofclaim 12, further comprising: a level sensor mounted to the conveyor,the level sensor configured to generate a level sensor signal indicatingsaid orientation of the conveyor relative to level.
 15. The radialstacking conveyor of claim 14, wherein said level sensor comprises aninclination sensor disposed to measure an inclination of the conveyoralong an X direction, the X direction being tangential to a radialtravel direction R of the conveyor.
 16. The radial stacking conveyor ofclaim 12, further comprising: a conveyor truss; a first hydraulic pump,said first hydraulic pump in fluid communication with said firstactuator; a conveyor lift cylinder disposed to modify a height of saidconveyor truss; and a second hydraulic pump, said second hydraulic pumpin fluid communication with said conveyor lift cylinder.
 17. The radialstacking conveyor of claim 16, wherein said first and second hydraulicpumps together comprise a tandem gear pump.
 18. The radial stackingconveyor of claim 12, wherein in said radial travel configuration thebase frame is supported by said first and second sets of radial travelwheels, wherein the first actuator is able to alternately raise andlower the first and second sets of radial travel wheels between atransport configuration and the radial travel configuration, the radialstacking conveyor further comprising: a transport wheel, wherein in saidtransport configuration the base frame is at least partially supportedby said transport wheel.
 19. The radial stacking conveyor of claim 18,wherein said flow control device comprises a valve.
 20. The radialstacking conveyor of claim 19, wherein said valve comprises anover-center valve.